Portable road signs find application around roadway repair and construction sites, giving warning of hazardous situations, detours, and the like. Stands for portable signs should be readily collapsible into a small space for storage, handling, and transportation. Maximized wind resistance, consistent with the available weight and design characteristics of the stand, is also a desired feature along with high-strength construction and a capability to accommodate signs of various sizes and shapes. In some instances, it may also be desirable to place a given sign at different places on the same stand for a reason such as to obtain the highest possible effective wind resistance under a given set of conditions.
A foremost consideration in design of such stands is the concern for safety which arises out of a need to protect both the work crew around the site and drivers of vehicles which might impact the sign. Efforts toward improving the safety of a sign stand are properly directed toward the following goals: reduction of the impact energy of a stand in motion, reduction of the probability of a direct impact of a vehicle with the stand, elimination of heavy items such as springs and housings where possible and inclusion of break-away features.
Various types of portable sign stands are disclosed in prior patents. U.S. Pat. No. 5,318,258, issued on Jun. 7, 1994, to Lang, discloses an elongated sign-holding mast supported by a multi-legged base. The legs are pivotally supported for movement and are secured in place by a retainer pin. Sprague in U.S. Pat. No. 5,208,585, issued on May 4, 1993, discloses a portable barrier filled with liquid and having vertically oriented sides and end walls with apertures for attachment of signs. U.S. Pat. No. 4,676,015, issued on Jun. 30, 1987, to Stoudt discloses a stand with a base, a lower staff, and an upper staff for receiving a sign. A spring asserts a force to control the deflection of the upper staff. U.S. Pat. No. 4,569,499, issued on Feb. 11, 1986, to Seely, discloses a frame member foe mounting a sign and a means to allow the sign to pivot or swing under side-wind loads by action of a resilient portion of the stand.
While many prior designs are available, further improvement is needed to obtain maximum versatility of application, stronger wind resistance, and high safety. In terms of capabilities of existing sign stands while operating at varying wind conditions, heavier stands equipped with springs and other apparatus can be effective at wind speeds up to 60 miles per hour, but their costs are relatively high. Simpler and lighter designs are less expensive, but their useful range has been up to about 10 miles per hour. It is desirable to provide a relatively low-cost design that would be effective in an intermediate wind speed range.